1. Field of the Invention
The present invention relates to key switches used for use in a keyboard input device, and more particularly, to key switches each having a cross-linked member.
2. Description of the Related Art
Various types of key switches suitable for lower-profile keyboard input devices have been recently proposed. In such key switches, a key top is supported by the upper ends of a pair of cross-linked lever members. The angle at which the lever members cross changes in response to the upward and downward movement of the key top.
For example, a key switch is disclosed in which a cross-linked member for guiding the upward and downward movement of a key top is formed by cross-linking one lever member, which is rotatably engaged at its upper end with the bottom of the key top, and the other lever member which is slidably engaged at its upper end with the bottom of the key top.
In this type of key switch, when an operator depresses the key top, the lever members are tilted and the cross-linked member is folded down. When the key top is moved down by a predetermined amount, an elastic member, such as a rubber click member, is pressed and buckled by the key top. Consequently, a switch device, such as a membrane switch, is depressed by the elastic member, thereby bringing about a switch-on state.
When the depressing force applied to the key top is terminated in this switch-on state, the buckled elastic member returns to its initial shape due to its inherent elastic characteristics. Consequently, the switch device returns to an off state and the key top is pushed up to its initial position while raising the tilted lever members.
According to such a configuration in which the key top is supported by the cross-linked member so that it can move up and down, it is possible to enhance operability and to substantially reduce the height of the switch, compared with a conventional key switch in which a key stem is slid along a guide wall.
In this key switch, however, the structure for supporting the lower end of the cross-linked member (a pair of lever members) is complicated. This requires substantial amounts of time to mount the cross-linked member and increases the costs.
After the cross-linked member is mounted on the switch device, such as a membrane switch, the key top is attached to the upper end of the cross-linked member, thereby completing the assembly operation of the key switch. Since the key top is large enough to cover the cross-linked member, however, it is difficult to visually check the assembly operation of properly engaging the upper ends of the lever members constituting the cross-linked member with the bottom of the key top. Therefore, and the checking operation must be performed using the experience and intuition of the operator.
That is, in order to quickly and precisely perform operations of rotatably engaging the upper end of one lever member with the bottom of the key top and slidably engaging the upper end of the other lever member with the bottom of the key top in a state in which the engaging portions are not visible, the operator must be highly skilled. Therefore, if the operator is unskilled, operating efficiency and reliability are seriously lowered.
Furthermore, the bottom of the key top is provided with a recess which points downward and is surrounded by a wall. In order to form therein a shaft groove or a slide groove to be engaged with the upper end of the cross-linked member and a pressing protuberance to be contacted with the elastic member, such as a rubber click member, a significantly complicated molding die is required and this increases the manufacturing cost of the key top.
Accordingly, the present invention has been made to solve the above problems in the conventional arts, and it is an object of the present invention to provide an inexpensive key switch which can be easily mounted and which improves productivity.
In order to achieve the above object, according to an aspect of the present invention, there is provided a key switch that includes a pair of lever members with intersections rotatably connected. An actuator rotatably engages the upper end of one of the lever members therewith and slidably engages the upper end of the other lever member therewith. A key top is retained by the actuator and a supported movably up and down by the lever members. An elastic member, such as a rubber click member, urges the key top upward via the actuator and a switch device, such as a membrane switch, performs a switching operation in response to the upward and downward movement of the key top.
When assembling the key switch, the upper end of the cross-linked member constituted by the lever members is engaged with the actuator beforehand. After the cross-linked member is mounted on the switch device, the bottom of the key top is held on the cross-linked member by a simple means, such as press fitting. This makes it possible to mount the key top more easily than in a conventional case in which the bottom of the key top is engaged with the cross-linked member. If the actuator has such a shape that its portion engaged with the cross-linked member is exposed, there is no problem. Therefore, the actuator can be easily engaged with the cross-linked member. Furthermore, since the bottom of the key top need not have an engaging portion to be engaged with the cross-linking member and a projection for pressing the elastic member, a complicated die is not necessary for molding the key top, which substantially reduces the cost of the die.
According to another aspect of the present invention, there is provided a key switch including a switch device, such as, a membrane switch, having a plurality of switch bodies, for example, each composed of an upper electrode and a lower electrode, consecutively arranged at predetermined intervals. A support member, such as a plate, is placed on the switch device so as to have through portions, support portions and switch pressing portions. The through portions, for example, may be through holes or cutouts. The support portions, such as louver portions, are formed at positions corresponding to the switch bodies of the switch device. The switch pressing portions are supported by the support portions of the support member so as to individually press the switch bodies, for example, the switch pressing portions each being composed of a cross-linked member. The key switch also includes an actuator, a rubber click member, and a key top.
In this key switch, the switch device has a plurality of switch bodies arranged consecutively, and the support member has a plurality of support portions and through portions arranged consecutively so as to support the switch pressing portions. The switch bodies are opposed to the through portions. Since the switch pressing portions supported by the support portions automatically correspond to the switch bodies, it is possible to reduce the number of components, to facilitate assembly operation, and to allow automatic assembly.
According to a further aspect of the present invention, there is provided a key switch including a pair of lever members, such as an inner lever member and an outer lever member, with intersections thereof rotatably connected. A key top is supported by the lever members so as to move up and down. An elastic member, such as a rubber click member, urges the key top upward. A switch device, such as a membrane switch, performs switching in response to the upward and downward movement of the key top and a plate, formed by bending (stamping) a metal plate, has a first louver portion that slidably engages the lower end of one of the lever members therewith and has a second louver portion that rotatably engages the lower end of the other lever member therewith.
In this case, the first and second louver portions for engaging the lower ends of the lever members can be simultaneously formed by bending a metal plate, and the shape of the plate is simple. This makes it possible to easily produce the plate, to improve productivity, and to reduce cost.
Preferably, the key switch further includes an actuator for rotatably engaging the upper end of one of the lever members therewith and slidably engaging the upper end of the other lever member therewith, and the key top is retained by the actuator.
In this case, it is only necessary in the assembly process to engage the upper end of the cross-linked member constituted by the lever members with the actuator beforehand and to hold the bottom of the key top on the actuator via a simple means, such as by press fitting, after the cross-linked member is mounted on the switch device. Therefore, the key top can be mounted more easily than in a conventional case in which the bottom of the key top is engaged with the cross-linked member. If the actuator has such a shape that its portion engaged with the cross-linked member is exposed, there is no problem. Therefore, the actuator can be easily engaged with the cross-linked member. Furthermore, since the bottom of the key top need not have an engaging portion to be engaged with the cross-linking member and a projection for pressing the elastic member, a complicated die is not necessary for molding the key top, which substantially reduces the cost of the die.
Preferably, the actuator has a retaining hole or a projection, the bottom of the key top has a projection or a retaining hole, and the projection is fitted in the retaining hole. This makes it possible to easily attach the key top to the actuator.
Preferably, the plate has a through portion, such as a through hole or a cutout, and a pressing protuberance formed in the elastic member that is placed above the through portion. The switch device is placed below the through portion, and the pressing protuberance and the switch device are opposed to each other via the through portion.
The pressing protuberance of the elastic member and the switch device are opposed to each other via the through portion of the plate, and the switch device is pressed and positioned by the plate. This makes it possible to maintain an appropriate opposing relationship between the switch device and the pressing protuberance of the elastic member.
The key switch may further include a base member, such as a holding plate for positioning and holding the plate, while the switch device is held between the base member and the plate. In this case, the opposing relationship between the plate and the switch device is properly maintained, and the switch device is protected by the plate and the base member.
According to a further aspect of the present invention, there is provided a key switch including a pair of lever members with intersections thereof rotatably connected. A key top is supported by the lever members so as to move up and down. A plate is provided for supportingly mounting the lever members thereon. A holding plate is provided for holding and retaining the plate. An elastic member urges the key top upward. A membrane switch performs switching in response to the upward and downward movement of the key top, and a support plate is provided for mounting the membrane switch thereon. According to this aspect of the invention, the plate and the holding plate have a through hole for inserting the elastic member therein, and the membrane switch is held between the holding plate and the support plate. It is possible to check whether the cross-linked member operates properly in such a configuration since the cross-linked member can be formed by mounting a pair of lever members as a unit on the plate. For this reason, defective cross-linked members will not be mounted, and it is possible to avoid wasting existing components and to prevent operability from being lowered during assembly. Moreover, since the plate for supportingly holding the cross-linked member can be placed on the holding plate, it is unnecessary to form louver portions in the support plate so as to engage with the bottom end of the cross-linked member, and to form multiple holes in the membrane switch so as to pass the louver portions therethrough. This ensures a sufficiently wide space in the membrane switch for a layout pattern and easily improves the degree of freedom in design and reliability.
Preferably, the plate has a first louver portion for rotatably engaging the lower end of one of the lever members therewith and a second louver portion for slidably engaging the lower end of the other lever member therewith. This allows the cross-linked member to operate smoothly.
Preferably, a plurality of pairs of lever members are supportingly mounted on the plate. In this case, since a unit having a plurality of cross linked members arranged in parallel can be obtained, it is possible to efficiently assemble key switches in the keyboard input device.
According to a still further aspect of the present invention, there is provided a key switch including a pair of lever members, such as an inner lever member and an outer lever member, with intersections thereof rotatably connected. A key top is supported by the lever members so as to move up and down. An elastic member, such as a rubber click member, urges the key top upward. A switch device, such as a membrane switch, performs switching in response to the upward and downward movement of the key top, and a plate having a first louver portion slidably engages the lower end of one of the lever members therewith, a second louver portion rotatably engages the lower end of the other lever member therewith, and a protuberance. The protuberance is formed adjacent to the leading end of the second louver portion, wherein the lower end of the other lever member is rotatably snapped into the second louver portion from between the leading end of the second louver portion and the protuberance.
In this case, it is possible to provide an inexpensive key switch which permits the lever members to be easily attached to the plate and which provides high productivity.
The key switch may further include an actuator for rotatably engaging the upper end of one of the lever members therewith and slidably engaging the upper end of the other lever member therewith, and the actuator may retain the key top.
In this case, it is only necessary in the assembly process to engage the upper end of the cross-linked member constituted by the lever members with the actuator beforehand and to hold the bottom of the key top on the actuator via a simple means, such as by press fitting, after the cross-linked member is mounted on the switch device. Therefore, the key top can be mounted more easily than in a conventional case in which the bottom of the key top is engaged with the cross-linked member. If the actuator has such a shape that its portion engaged with the cross-linked member is exposed, there is no problem. Therefore, the actuator-can be easily engaged with the cross-linked member. Furthermore, since the bottom of the key top need not have an engaging portion to be engaged with the cross-linking member and a projection for pressing the elastic member, a complicated die is not necessary for molding the key top, which substantially reduces the cost of the die.
Preferably, the actuator has a retaining hole or projection, the bottom of the key top has a projection or a retaining hole, and the projection is fitted in the retaining hole. This allows the key top to be easily attached to the actuator.
Preferably, the plate has a through portion, such as a through hole or a cutout, a pressing protuberance formed in the elastic member is placed above the through portion, the switch device is placed below the through portion, and the pressing protuberance and the switch device are opposed to each other via the through portion. This makes it possible to maintain an appropriate opposing relationship between the switch device and the pressing protuberance of the elastic member.
The key switch may further include a base member, such as a holding plate, for positioning and holding the plate, and the switch device may be held between the base member and the plate. In this case, the opposing relationship between the plate and the switch device is properly maintained, and the switch device is protected by the plate and the base member.
Further objects, features, and advantages of the present invention will be apparent from the following description of the preferred embodiments with reference to the attached drawings.